Lazio cruised to a 3-0 victory over city rivals Roma on Friday, equalling their best ever derby victory in Serie A.
The win moved Lazio up to seventh place on 31 points, just two behind champions Juventus in fourth.
Roma stay third with 34 points, but are six points off leaders Milan having also played a game more.
Ciro Immobile opened the scoring in the 14th minute for his 12th goal of the season.
Luis Alberto, in the 23rd and 67th minutes, scored the other two, both with precise strikes.
Roma, who had drawn 2-2 with second-placed Inter last weekend, were rescued from further punishment by goalkeeper Paul Lopez who pulled off a series of fine second-half saves.
“This season, it was a bit more important than usual, because we weren’t doing as well in Serie A as we wanted,” Spanish star Alberto said.
“The last three or four games have been much better, we improved a great deal, and we confirmed that in the derby.
“We showed a winning mentality and want to keep this momentum going.”
Friday’s game was the first derby for new Roma owner Dan Friedkin, but the performance was desperately familiar.
Having lost heavily already this season to top six rivals Napoli (4-0) and Atalanta (4-1), Roma were undone by a far more aggressive Lazio side.
The first goal came off an error when Manuel Lazzari stole the ball from under the feet of Roma defender Roger Ibanez to allow Immobile to finish.
Lazzari also created the second goal, finding his feet after initially slipping to free Alberto to score with Ibanez again at fault.
Lopez’s heroics were unable to prevent Alberto from adding his second.
“I think in the opening minutes, we had the right approach, but against a side like Lazio, it’s difficult to recover if you gift them two goals,” Roma coach Paulo Fonseca said.
Roma could be overtaken in the table later this weekend when Juventus face Inter.